Mammalian reproductive function is regulated by hypothalamic neurons that secrete Kisspeptin (Kp), a neuropeptide that stimulates gonadotropin-releasing hormone (GnRH) secretion, triggering pituitary gonadotrophins (LH and FSH) and gonadal steroids. This study evaluated the effect of Kisspeptin-10 (Kp10) on ovulation induction in rabbits, comparing its efficacy with that of the GnRH analogue gonadorelin. Multiparous New Zealand White × California does were assigned to three groups: control group (0.5 % saline solution, i.v.), GnRH group (20 μg gonadorelin, i.m.), and Kp10 group (250 μg Kp10, i.v.). Kp10 induced ovulation in 87.5 % of does, matching the response observed in the GnRH group, with a comparable number of corpora lutea (CL) per ovulated doe (12.9 ± 1.4 vs 14.6 ± 1.4 CL/doe, respectively). On day 7, plasma progesterone (P4) was significantly higher in ovulated GnRH-treated does than in Kp10-treated ones (25.12 ± 4.17 vs 9.47 ± 4.17 ng/mL; p < 0.0211), while non-ovulated controls exhibited minimal P4 concentrations (0.86 ± 0.12 ng/mL). Plasma estradiol (E2) levels showed no significant differences across days or groups, with mean values of 32.74 ± 4.33 pg/mL on day 0 and 37.27 ± 5.49 pg/mL on day 7, respectively. Histological analysis confirmed that Kp10 promoted preovulatory follicle development and CL formation, mirroring GnRH effects. Additionally, Kp10 enhanced angiogenesis, indicated by increased vascular endothelial growth factor (VEGF) expression in more developed follicles and CL. These results suggest that Kp10 could be an alternative to GnRH for ovulation induction in rabbits, although further studies are needed to explore optimal analogues, doses, and administration routes.

The aim of this study was to analyze how recombinant rabbit NGF (Nerve Growth Factor) encapsulated in chitosan (rrβNGFch) affects sperm viability, motility, capacitation, acrosome reaction (AR), kinetic traits, and apoptosis after 30 min and 2 h of storage. Specific intracellular signaling pathways associated with either cell survival, such as protein kinase B (AKT) and extracellular signal-regulated kinases 1/2 (ERK1/2), or programmed cell death, such as c-Jun N-terminal kinase (JNK), were also analyzed. The results confirmed the effect of rrβNGFch on capacitation and AR, whereas a longer storage time (2 h) decreased all qualitative sperm traits. AKT and JNK did not show treatment-dependent activation and lacked a correlation with functional traits, as shown by ERK1/2. These findings suggest that rrβNGFch may promote the functional activation of sperm cells, particularly during early incubation. The increase in capacitation and AR was not linked to significant changes in pathways related to cell survival or death, indicating a specific action of the treatment. In contrast, prolonged storage negatively affected all sperm parameters. ERK1/2 activation correlated with capacitation, AR, and apoptosis, supporting its role as an NGF downstream mediator. Further studies should analyze other molecular mechanisms of sperm and the potential applications of NGF in assisted reproduction.